Papers by Keyword: Auger Electron Spectroscopy (AES)

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Authors: B. Chen, Peter E.J. Flewitt, David John Smith, C.M. Younes
Abstract: A preliminary sensitivity examination of the ductility exhaustion based creep damage prediction model, currently used in the R5 high temperature assessment procedure, showed that material property inputs had significant effects on damage prediction. In the present work, the link between the microstructural factors and the susceptibility to inter-granular high temperature creep failure is considered. The latter was judged to be associated with the low creep ductility. Here, the longitudinal section of a creep specimen and the fracture surface were examined. Auger electron spectroscopy was used to investigate the grain boundary composition in this specimen, which failed after a creep test of 1038h at 550°C under a triaxial stress state. The present results demonstrate that there is a possibility to correlate the susceptibility to high temperature inter-granular fracture from the low temperature fracture investigations. Finally, the susceptibility of the pre-treated 316H stainless steel to inter-granular high temperature failure and the contribution to the creep damage model are briefly discussed.
Authors: S. Aggarwal, R.K. Mohindra, P.K. Ghosh, M.C. Bhatnagar
Authors: Kalevi Kokko, Sasuma Granroth, M.H. Heinonen, R.E. Perälä, T. Kilpi, Edwin Kukk, M.P.J. Punkkinen, E. Nurmi, Matti Ropo, Antti Kuronen, Levente Vitos
Abstract: Surface and interface properties of Fe-Cr, Fe-Al, and Fe-Cr-Al are studied using Exact Muffin-Tin Orbitals and Monte Carlo methods and with x-ray photoelectron and Auger electron techniques. Surface composition is investigated as a function of oxidation (heating) time. Hard x ray photoelectron spectroscopy (HAXPES) is used to scan non destructively the compositions below the surface. It is found that Cr boosts the Al segregation to the surface.
Authors: Gabriel A. López, Eric J. Mittemeijer
Abstract: A systematic investigation of the segregation of Bi at both free surfaces and grain boundaries in Cu, under identical conditions, is reported. The problem of Bi evaporation upon Bi segregation at free surfaces was overcome using a special method for sample preparation. Cu bicrystals containing deliberately made internal cavities at the grain boundary were doped with Bi, annealed at temperatures between 1073 and 1223 K, and broken along the grain boundary in an ultrahigh vacuum chamber for Auger electron spectroscopy. For the first time, the equilibrium surface segregation of Bi in Cu has been measured. The segregation at the free surface was found to be stronger than the segregation at the grain boundary.
Authors: C. Akita, S. Sekiguchi, M. Fujimoto, Hajime Haneda, M. Tanaka
Authors: D.E. Luzzi, D. Imamura, Haruyuki Inui, E.P. George, L. Heatherly, Hiroyuki Y. Yasuda, H. Mori, Masaharu Yamaguchi
Authors: I. Beszeda, Dezső L. Beke, E.G. Gontier-Moya, Yuri S. Kaganovsky, D. Ianetz
Abstract: We propose a simple method for calculation of surface self-diffusion coefficients using kinetic data on the decay of thin films – void growth and transformation of the island shape to the equilibrium. Calculations are made taking into account equilibrium wetting angle of the film on a substrate. The kinetic data on the decay of Pd thin films on sapphire and silica substrates were obtained using Auger electron spectroscopy. By in situ monitoring the intensity of the Auger signal from the film, three different stages of the decay could be distinguished. The surface self-diffusion coefficients were calculated for the temperature range 583 – 823 K. The values of the surface diffusion coefficients and the activation energies are discussed compared to those obtained by other methods.
Authors: Biliana Georgieva, Irena Podolesheva, Georgi Spasov
Abstract: Thin films (40-60 nm) prepared by co-evaporation of Sn and TeO2 were studied as ethanol gas sensors. In the as-deposited state, the films thus obtained are amorphous and consist of mixed Te and Sn oxides, doped with Te, Sn, and/or SnTe (depending on the atomic ratio between Sn and Te (RSn/Te)), due to interaction between the two substances during the co-deposition. After stepwise thermal treatment of films with RSn/Te ≈ 2.3 up to 360oC (by 40oC steps, for 15 minutes at each temperature) nanocrystalline films, built up of a mixture of SnO2, TeO2 and unstoichiometric Sn oxide were obtained. The Pt-doping was realized by thermal evaporation in a separate vacuum cycle, after the annealing. To study the film composition and structure as well as the volume distribution of the elements different electron microscopy techniques (TEM, SAED) and analytical methods (EDS in SEM, AES) were applied. The sensitivity towards ethanol vapours was investigated as a function of the substrate temperature (T) in the range from 20oC to 200oC. High sensitivity has been observed for Pt-doped films at T = 120oC. No cross sensitivity to relative humidity (RH [%]) was observed at this temperature. Further improvement of the sensitivity could be obtained by optimization of the thermal processing, Pt-doping and working temperature.
Authors: M. Gao, Sergey P. Tumakha, T. Onishi, Susumu Tsukimoto, Masanori Murakami, Leonard J. Brillson
Abstract: We have used depth-resolved cathodoluminescence and Auger electron spectroscopies, DRCLS and AES, respectively, to probe the electronic structure and the composition of Ti/Al ohmic contacts to p-type SiC on a nanometer scale. A continuous Ti-Si-C compound layer was observed using the Auger depth profile. No interfacial Al segregation was found. The secondary electron threshold technique showed a continuous decrease in work function from the p-type SiC to the Ti-Si-C compound layer. Our results support an ohmic contact mechanism by an intermediate semiconductor layer which reduces the otherwise large interfacial Schottky barrier height. DRCLS revealed a ~2.78 eV sub-band gap transition enhanced by interfacial reaction in the near-interface SiC, suggesting the formation of additional C or Si vacancies.
Authors: Shun Ichiro Tanaka, K. Takahashi, C. Akita, Hajime Haneda, M. Tanaka
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